Similar to the Top50 scoreboard you could see on, say, a song page (example: http://osu.ppy.sh/s/20290), why not implement a similar feature that shows every (or at least the top 50) songs a user has played, sorted by the global rank the user has? Obviously, not every song would be recorded, but the best score per beatmap collection (Difficulties, etc) of ranked or approved songs
Table columns would include (mostly like the song Top50 rankings)
Global rank
Song rank
Accuracy
Beatmap name
Beatmap difficulty
Max combo
300 / 100 / 50
Elite beat! / Beat! / Miss
Mods
This seems like it would be a neat idea to look through your songs and see the ranks you've achieved.
Table columns would include (mostly like the song Top50 rankings)
Global rank
Song rank
Accuracy
Beatmap name
Beatmap difficulty
Max combo
300 / 100 / 50
Elite beat! / Beat! / Miss
Mods
This seems like it would be a neat idea to look through your songs and see the ranks you've achieved.